Stage --harmony-async-iteration

Bug: v8:5855
Change-Id: Ie783318b2297f85a9f102e1266dfc1fac406435a
Reviewed-on: https://chromium-review.googlesource.com/466107
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47384}

src/flag-definitions.h

@@ -194,7 +194,6 @@ DEFINE_IMPLICATION(es_staging, harmony)
   V(harmony_function_sent, "harmony function.sent")                   \
   V(harmony_do_expressions, "harmony do-expressions")                 \
   V(harmony_class_fields, "harmony public fields in class literals")  \
-  V(harmony_async_iteration, "harmony async iteration")               \
   V(harmony_promise_finally, "harmony Promise.prototype.finally")
 
 #ifdef V8_INTL_SUPPORT
@@ -217,7 +216,8 @@ DEFINE_IMPLICATION(es_staging, harmony)
   V(harmony_restrict_constructor_return,                                \
     "harmony disallow non undefined primitive return value from class " \
     "constructor")                                                      \
-  V(harmony_dynamic_import, "harmony dynamic import")
+  V(harmony_dynamic_import, "harmony dynamic import")                   \
+  V(harmony_async_iteration, "harmony async iteration")                 \
 
 // Features that are shipping (turned on by default, but internal flag remains).
 #define HARMONY_SHIPPING(V)                                              \